Rail with friction control tread surface for inner rail, rail with friction control tread surface for outer rail, and permanent way

ABSTRACT

This rail with a friction control tread surface for an inner rail includes an inner wheel contract surface that is provided so as to be curved along a line shape of a permanent, and is subjected to being in contact with an inner wheel of the rail car which rolls therealong. A plurality of grooves extending in a direction orthogonal to the line shape are formed on the inner wheel contract surface. This rail with a friction control tread surface for an outer rail includes an outer wheel contact surface that is provided so as to be curved along a line shape of a permanent way, and is subjected to being in contact with an outer wheel of the rail car which rolls therealong. A plurality of grooves extending in a direction of the line shape are formed on the outer wheel contract surface.

RELATED APPLICATIONS

The present application is a National Phase of PCT/JP2014/061841, filed Apr. 28, 2014, and claims priority of Japanese Patent Application No. 2013-181179, filed on Sep. 2, 2013.

TECHNICAL FIELD

The present invention relates to a rail with a friction control tread surface for an inner rail, and a rail with a friction control tread surface for an outer rail that are provided in a permanent way along which a rail car travels, and the permanent way including thereof.

BACKGROUND ART

When a railroad car travels along a curved section of a permanent way, due to a condition in which a wheel (an inner wheel) that rolls along an inner rail and a wheel (an outer wheel) that rolls along an outer rail rotate at the same speed of rotation and the difference between the radii of rotation of the inner rail and the outer rail, a difference between circumferential speeds of the inner wheel and the outer wheel is generated. Then, a frictional force operates between the inner rail and the inner wheel in a direction orthogonal to a line shape of the permanent way due to the influence of such a difference between circumferential speeds, or due to centrifugal force. Moreover, since the outer wheel slips while rolling along the outer rail, a frictional force operates between the outer rail and the outer wheel in a direction of the line shape of the permanent way.

Accordingly, there are problems such as hindrance to smooth travelling at the curved section, generation of a squeaking noise, and abrasion of rails and wheels caused by remarkable lateral pressure, due to the frictional force applied to the inner wheel and the outer wheel. Specifically, as illustrated in FIG. 5, a wavelike abrasion 101 is generated on the top surface of an inner rail 100, and thus, a rolling noise is generated when the inner wheel rolls therealong. In addition, a flange of the outer wheel comes into contact with a side surface of an outer rail 110 on the inner rail 100 side, thereby generating a side abrasion 111 and a contact noise.

In order to solve the problems, in the related art, there is a known method in which the frictional force between a wheel and a rail is reduced by performing watering, oiling, or injecting of a lubricant, and the like between the wheel and the rail. In addition, PTL 1 discloses a rail in which grooves are obliquely formed on the top surface with respect to a travelling direction in order to reduce noise which is generated when a rail car travels therealong.

Reduction of the above-described frictional force generated between a rail and a wheel can be achieved by reducing the contact area between the wheel and the rail. In this regard, since the grooves are formed in the rail disclosed in PTL 1, it is possible to reduce the contact area between the rail and the wheel.

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No. 2005-139605

SUMMARY OF INVENTION Technical Problem

However, according to the invention of PTL 1, grooves are formed in a direction different from the direction of the frictional force generated between a wheel and a rail. Therefore, there is a possibility that reduction of a frictional force cannot be sufficiently achieved. Moreover, there is a possibility that a rail car travels in both directions of the extension direction of the rail. In the grooves disclosed in PTL 1, the formation pattern of the grooves changes when the travelling direction of the rail car is changed. Accordingly, due to the difference of the travelling direction of the rail car, a difference in the effect of reducing frictional force occurs to the extent that there is a possibility that the effect of reducing frictional force cannot be stably obtained.

The present invention provides a rail with a friction control tread surface for an inner rail, a rail with a friction control tread surface for an outer rail, and a permanent way in which the frictional force can be reduced between the rail and the wheel with a simple structure.

Solution to Problem

According to a first aspect of the present invention, a rail with a friction control tread surface for an inner rail is provided so as to be curved along a line shape of a permanent way along which a rail car travels and includes an inner wheel contact surface with which an inner wheel of the rail car comes into contact so as to roll therealong. A plurality of grooves extending in a direction orthogonal to the line shape while being arranged at intervals in a direction of the line shape are formed on the inner wheel contact surface.

According to such a rail with a friction control tread surface for an inner rail (hereinafter, simply referred to as the inner rail), when a rail car travels along a section where the inner rail is curved along the line shape of the permanent way, that is, a curved section of the permanent way, the inner wheel which is a wheel positioned on the inner side of the curve rolls along the top of the inner wheel contact surface. Here, since the grooves are formed on the inner wheel contact surface, a contact area between the inner wheel contact surface and the inner wheel can be reduced. In addition, since the grooves are formed so as to be orthogonal to the line shape of the permanent way, when the rail car travels the curved section, it is possible to reduce the frictional force generated in a direction orthogonal to the direction of the line shape of the permanent way. Moreover, as the grooves are formed so as to be orthogonal to the direction of the line shape, even in a case where the traveling direction of a rail car is changed, the formation pattern of the grooves does not change. Therefore, regardless of the travelling direction of a rail car, it is possible to stably obtain the effect of reducing the frictional force.

According to a second aspect of the present invention, the grooves may be formed on only the inner wheel contact surface.

When a rail car travels the curved section, the rail car travels in a state where the inner wheel leans toward the outer side in the radial direction of rotation due to a difference between circumferential speeds of the inner wheel and an outer wheel, and centrifugal force. Therefore, the inner wheel does not comes into contact with the entire top surface of the inner rail and comes into contact with only the inner wheel contact surface. Accordingly, it is possible to efficiently reduce the frictional force between the inner wheel and the inner wheel contact surface by forming the grooves on only the inner wheel contact surface.

According to a third aspect of the present invention, a rail with a friction control tread surface for an outer rail is provided so as to be curved along the line shape of the permanent way along which a rail car travels and includes an outer wheel contact surface with which the outer wheel of the rail car comes into contact so as to roll therealong. A plurality of grooves extending in the direction of the line shape while being arranged at intervals in the direction orthogonal to the line shape, are formed on the outer wheel contact surface.

When a rail car travels a section where the rail with a friction control tread surface for an outer rail is curved along the line shape of the permanent way, that is, a curved section of the permanent way, the outer wheel which is a wheel positioned on the outer side of the curve rolls along the top of the outer wheel contact surface. Here, since the grooves are formed on the outer wheel contact surface, a contact area between the outer wheel contact surface and the outer wheel can be reduced. In addition, since the grooves are formed so as to be along the line shape of the permanent way when the rail car travels the curved section, it is possible to reduce the frictional force generated in the direction of the line shape of the permanent way. Moreover, as the grooves are formed so as to be along such a line shape, even in a case where the traveling direction of a rail car is changed, the formation pattern of the grooves does not change. Therefore, regardless of the travelling direction of a rail car, it is possible to stably obtain the effect of reducing the frictional force.

According to a fourth aspect of the present invention, the permanent way includes the rail with a friction control tread surface for an inner rail and the rail with a friction control tread surface for an outer rail.

According to such a permanent way, it is possible to reduce the frictional force in the direction orthogonal to the line shape of the permanent way between the inner wheel contact surface and the inner wheel in the rail with a friction control tread surface for an inner rail, and it is possible to reduce the frictional force in the direction of the line shape of the permanent way between the outer wheel contact surface and the outer wheel in the rail with a friction control tread surface for an outer rail. Therefore, it is possible to more effectively reduce the frictional force.

Advantageous Effects of Invention

According to a rail with a friction control tread surface for an inner rail, a rail with a friction control tread surface for an outer rail, and a permanent way described above, the frictional force between a wheel and a rail can be reduced with a simple structure by forming grooves in a direction of a line shape of the permanent way.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a top view illustrating a permanent way and wheels which roll along the top of the permanent way according to an embodiment of the invention.

FIG. 2 is a perspective view illustrating the permanent way according to the embodiment of the invention.

FIG. 3 is a front view illustrating the permanent way and the wheels which roll along the top of the permanent way according to the embodiment of the invention

FIG. 4 is a perspective view illustrating a permanent way according to a modification example of the embodiment of the invention.

FIG. 5 is a perspective view illustrating a state of abrasion of an inner rail and an outer rail on the assumption that there is no groove formed in the inner rail and the outer rail.

DESCRIPTION OF EMBODIMENT

Hereinafter, a permanent way 1 according to an embodiment of the present invention will be described.

As illustrated in FIG. 1, the permanent way 1 allows a railroad car (hereinafter, referred to as a rail car) to travel therealong by causing wheels 20 of a carriage provided at a lower portion of the rail car to roll therealong.

The permanent way 1 has a straight section 2 and a curved section 3. In the curved section 3, as a pair of rails 10, the permanent way 1 includes an inner rail 11 (a rail with a friction control tread surface for an inner rail) which is positioned on the inner side of a curve and an outer rail 15 (a rail with a friction control tread surface for an outer rail) which is positioned on the outer side of the curve. The inner rail 11 and the outer rail 15 are provided so as to be curved along a line shape of the permanent way 1.

The inner rail 11 and the outer rail 15 are supported from below by ballast, railroad ties, and permanent way slabs (not illustrated).

As illustrated in FIG. 2, the inner rail 11 has a top surface 12 which is subjected to being in contact with a tread surface 21 a of an inner wheel 21 which is the wheel 20 positioned on the inner side of the curve (refer to FIGS. 1 and 3), and the inner rail 11 is a copper-made member which is formed so as to have an I-shaped cross-section orthogonal to the extension direction of the inner rail 11. The top surface 12 is formed to be flat so as to allow the inner wheel 21 to roll therealong.

Here, as illustrated in FIG. 3, when a rail car travels the curved section 3, due to the difference between circumferential speeds of the inner wheel 21 and an outer wheel 22, and due to a centrifugal force, the inner wheel 21 rolls along the top surface 12 of the inner rail 11 in a state of leaning toward the outer side in the radial direction of rotation. In this manner, on the top surface 12 of the inner rail 11, a portion with which the tread surface 21 a of the inner wheel 21 comes into contact when a rail car travels is referred to as an inner wheel contact surface 13.

Then, as illustrated in FIG. 2, on the inner wheel contact surface 13, a plurality of grooves 14 which extend in the width direction orthogonal to the line shape direction so as to be parallel to each other while being arranged at intervals in the line shape direction of the line shape of the permanent way 1 which is the extension direction of the permanent way 1. In the present embodiment, each of the grooves 14 is formed not only on the inner wheel contact surface 13 but also on the entire top surface 12 of the inner rail 11, that is, throughout the entire area from one end side to the other end side in the orthogonal direction. In addition, the grooves 14 are regularly formed at equal intervals from each other in the line shape direction.

The outer rail 15 has a top surface 16 with which the wheel 20 positioned on the outer side of the curve, that is, a tread surface 22 a of the outer wheel 22 comes into contact. Similar to the inner rail 11, the outer rail 15 is a copper-made member which is formed so as to have an I-shaped cross-section perpendicular to the extension direction of the outer rail 15. The top surface 16 is formed to be flat so as to allow the outer wheel 22 to roll therealong. Hereinafter, the top surface 16 is referred to as an outer wheel contact surface 17.

In addition, on the outer wheel contact surface 17 of the outer rail 15, a plurality of grooves 18 which extend in the direction of the line shape of the permanent way 1 so as to be parallel to each other while being arranged at intervals in the width direction. The grooves 18 are formed on the entire outer wheel contact surface 17 which is the top surface 16 of the outer rail 15. In addition, the grooves 18 are regularly provided at equal intervals from each other in the width direction.

According to such a permanent way 1, when a rail car travels the curved section 3 of the permanent way 1, the inner wheel 21 rolls along the top of the inner wheel contact surface 13. Here, since the grooves 14 are formed on the entire top surface 12 of the inner rail 11, it is possible to reduce the contact area between the inner wheel contact surface 13 and the inner wheel 21.

Here, an abrasion amount of the inner wheel contact surface 13 of the inner rail 11 is represented by R (mm), a specific abrasion amount is represented by K (mm³/Nm), surface pressure applied to the inner wheel contact surface 13 of the inner rail 11 from the inner wheel 21 is represented by P (MPa), a slip speed which is a relative speed between the inner wheel 21 and the inner rail 11 is represented by V (m/min), and a time taken for the inner wheel 21 to roll along the inner rail 11 is represented by T (min). Then, an abrasion amount of the inner rail 11 can be expressed by the following Expression (1).

R=K×P×V×T   (1)

Generally, the specific abrasion amount K indicates abrasion volume (mm³) of a material when the material is abraded by 1 (m) in a state where a force of 1 (N) is applied to the material.

Therefore, the specific abrasion amount K can be reduced by reducing the contact area between the inner wheel contact surface 13 of the inner rail 11 and the inner wheel 21. As a result, it is possible to reduce the abrasion amount R of the inner rail 11.

Moreover, while a rail car travels along the curved section 3, frictional force is generated in the width direction between the inner rail 11 and the inner wheel 21. Then, since the grooves 14 in the inner rail 11 are formed in the width direction, it is possible to effectively reduce the frictional force in the width direction.

Then, since the grooves 18 are formed on the outer wheel contact surface 17 of the outer rail 15, it is possible to reduce the contact area between the outer wheel contact surface 17 and the outer wheel 22. Moreover, it is possible to reduce the specific abrasion amount K. As a result, it is possible to reduce the abrasion amount R of the outer rail 15 in accordance with the above-described Expression (1).

In addition, while a rail car travels along the curved section 3, frictional force is generated in the line shape direction between the outer rail 15 and the outer wheel 22. Then, since the grooves 18 in the outer rail 15 are formed in the line shape direction, it is possible to effectively reduce the frictional force in the line shape direction.

In addition, as the grooves 14 are formed in the width direction in the inner rail 11 and the grooves 18 are formed in the line shape direction in the outer rail 15, even in a case where the travelling direction of a rail car is changed, the formation pattern of the grooves 14 and 18 does not change. Therefore, regardless of the travelling direction of a rail car, it is possible to stably obtain the effect of reducing the frictional force.

According to the permanent way 1 of the present embodiment, as the grooves 14 and 18 are formed in the direction of the line shape of the permanent way 1, it is possible to reduce the frictional force between the wheels 20 and the rails 10 with a simple structure.

Here, as illustrated in FIG. 4, the grooves 14 of the inner rail 11 may be formed on only the inner wheel contact surface 13 in the top surface 12 of the inner rail 11. In other words, the grooves 14 are formed in the orthogonal direction from the end portion on the outer rail 15 side positioned on the outer side of the radial direction of rotation, to an intermediate position of the top surface 12 of the inner rail 11.

As described above, when a rail car travels along the curved section 3, the inner wheel 21 rolls along the top of the inner rail 11 in a state of leaning toward the outer side in the radial direction of the radius of rotation. Accordingly, the tread surface 21 a of the inner wheel 21 comes into contact with only the inner wheel contact surface 13.

Therefore, it is possible to effectively achieve reduction of the frictional force between the inner wheel 21 and the inner wheel contact surface 13 by forming the grooves 14 on only the inner wheel contact surface 13.

Hereinbefore, the embodiment of the present invention has been described in detail. However, some design changes can be made without departing from the scope of the technical idea of the present invention. For example, the grooves 14 of the inner rail 11 and the grooves 18 of the outer rail 15 are not necessarily formed at equal intervals in a regular manner. However, when the degree of irregularity of intervals between the grooves 14 and 18 becomes significant, there is a possibility that the occurrence of vibration generated when the wheels 20 roll along the rails 10 is promoted, thereby increasing the abrasion of the rails 10 and the wheels 20. Therefore, it is preferable that the grooves 14 and 18 are regularly formed at equal intervals from each other.

In addition, the grooves 14 and 18 are not necessarily formed on both the inner rail 11 and the outer rail 15. The grooves 14 and 18 may be formed in only one thereof.

INDUSTRIAL APPLICABILITY

According to a rail with a friction control tread surface for an inner rail, a rail with a friction control tread surface for an outer rail, and a permanent way described above, the frictional force between a wheel and a rail can be reduced with a simple structure by forming grooves in a direction of a line shape of the permanent way. 

1. A rail with a friction control tread surface for an inner rail, comprising: an inner wheel contact surface that is provided so as to be curved along a line shape of a permanent way along which a rail car travels, and is subjected to being in contact with an inner wheel of the rail car which rolls therealong, wherein a plurality of grooves extending in a direction orthogonal to the line shape while being arranged at intervals in a direction of the line shape are formed on the inner wheel contact surface.
 2. The rail with a friction control tread surface for an inner rail according to claim 1, wherein the grooves are formed on only the inner wheel contact surface.
 3. A rail with a friction control tread surface for an outer rail, comprising: an outer wheel contact surface that is provided so as to be curved along a line shape of a permanent way along which a rail car travels, and is subjected to being in contact with an outer wheel of the rail car which rolls therealong, wherein a plurality of grooves extending in a direction of the line shape while being arranged at intervals in a direction orthogonal to the line shape are formed on the outer wheel contact surface.
 4. A permanent way comprising: the rail with a friction control tread surface for an inner rail according to claim 1; and a rail with a friction control tread surface for an outer rail comprising: an outer wheel contact surface that is provided so as to be curved along a line shape of a permanent way along which a rail car travels, and is subjected to being in contact with an outer wheel of the rail car which rolls therealong, wherein a plurality of grooves extending in a direction of the line shape while being arranged at intervals in a direction orthogonal to the line shape are formed on the outer wheel contact surface.
 5. A permanent way, comprising: the rail with a friction control tread surface for an inner rail according to claim 2; and a rail with a friction control tread surface for an outer rail, comprising: an outer wheel contact surface that is provided so as to be curved along a line shape of a permanent way along which a rail car travels, and is subjected to being in contact with an outer wheel of the rail car which rolls therealong, wherein a plurality of grooves extending in a direction of the line shape while being arranged at intervals in a direction orthogonal to the line shape are formed on the outer wheel contact surface. 